The present application is related to a touch or near touch sensing device structure, and finds particular application in connection an improved projective capacitive touch and/or near touch-sensing device and will be described with particular reference thereto. It is to be understood, however, that it also finds application in other usage scenarios, and is not necessarily limited to the aforementioned exemplary embodiment.
Touch and near touch user interfaces have been an essential element to the popularity of smartphones and tablets as well as other devices. A conventional projective capacitive sensing device is made by a matrix of diamond shaped conductive pads. There is a gap between each row and column pad, which forms a coplanar capacitor that acts as the sending aperture. A drive signal can be applied to one of the pads, on either the row or the column, and, by capacitive coupling, the signal is picked up from the other pad. When a finger touches or nears a panel having these configurations, it distorts the local electrostatic field at that point causing a measurable change in capacitance.
As touch and near touch sensing technology has developed, the cost of the sensor device has steadily dropped. As a result, inexpensive touch sensing devices can be used in broad applications, not only for computer or smartphone interfaces, but also for a variety of things that may be connected to the internet cloud services.
Projected capacitive sensing is able to sense a finger touch or near touch through a thin interlayer such as a glove. In addition to touch or near touch sensing, the capacitive aperture sensing is sensitive to surface textures and therefore can be used as a texture sensor. However, the effective sensing geometry is at the edges of the diamond pad, which forms the sensing gap with a neighboring pad in the conventional device.